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Controlling Listeria in Ready-to-Eat Products: 10 Helpful Measures You Can Implement in Your Plant
by Beth McKew
Previous issues of Small Plant News (Vol. 3, No. 11 and 12) featured articles describing elements of effective control programs
for Listeria monocytogenes (Lm), a bacterial pathogen that can contaminate post-lethality exposed ready-to-eat (RTE) meat and poultry
products, and which has been the cause of several outbreaks of foodborne illness. Effective control programs for Lm will
include preventive measures to eliminate cross contamination between RTE and non-RTE products, the design and implementation of a sanitation
program focusing on common bacterial harborage sites, and strict adherence to temperature controls.
Small Plant News has outlined 10 proactive measures you can take to control contamination from Lm in an
RTE environment. The following steps are not listed in any particular order, but if you implement them collectively,
you can further protect your customers and your business.
Separation of Raw and RTE Products
Ideally, RTE and raw areas should be separated by physical barriers (walls) with separate air handling,
employees, equipment, utensils, tools, etc. However, if this is not possible, then RTE and raw processing areas
should be separated by time or space. For example, schedule RTE processing on a different day than raw processing.
Or, if processing on different days is not possible, always schedule the production of RTE products first, followed by raw products.
Also consider using separate equipment for RTE and raw processing. Or, if separate equipment is not possible, use equipment for
RTE processing first, followed by equipment for raw processing.
In establishments that produce FSIS and U.S. Food and Drug Administration (FDA)-regulated products, it may also be advisable to
separate the products to maintain the safety and integrity of FSIS-regulated products.
Hands or gloves can readily transfer Lm from one surface, person, or food product to another.
Washing hands and sanitizing gloves before resuming workplace duties after breaks will reduce the spread of bacteria. Employees
should be trained and retrained on hygienic practices and proper hand washing techniques on a regular basis. Monitoring your
employees to observe if they are following personal hygiene practices in-plant is another important aspect of controlling Lm.
If you assign different personnel for RTE and raw processing, restrict employee travel to and from non-RTE areas during RTE
processing. Avoid passing raw product through RTE areas and RTE product through raw areas. All these measures will help
prevent the contamination of RTE product with Lm.
In addition to restricting access to RTE processing areas, using color-coded coats in RTE areas and non-RTE
areas will further reduce the risk of bringing Lm into RTE processing areas. Mandatory footbaths, clean gloves,
hairnets, and clean unused coats upon returning to the RTE processing area are additional preventive measures that will
also minimize the spread of this pathogen.
Maintaining sanitation in the RTE processing environment is crucial to controlling Lm. Lm can form
harborates in areas that are not thoroughly cleaned and spread to food contact surfaces and product. Keep records of sanitation
procedures to be used for processing RTE products that are covered by the Listeria rule as required in 9 Code of Federal
Regulations (CFR) Part 416. Also, monitor the performance of sanitation procedures and maintain records of sanitation
procedures performed in RTE processing areas, as well as throughout your plant. These actions may shed some light
on any lapses in procedure or identify the need for employee training or changes to sanitary procedures. Intensified
sanitation should be performed in response to positive test results from Listeria testing programs. By increasing
the frequency of sanitation, breaking down equipment for further cleaning, and heating or steam cleaning large pieces
of equipment, establishments can better address possible harborage and cross contamination in the establishment.
Temperatures in processing areas and packaging rooms should be maintained and regularly monitored and recorded, as stated
in your Hazard Analysis and Critical Control Point (HACCP) plan, Sanitation Standard Operating Procedures (SSOP),
and/or prerequisite programs, to prevent Lm growth in the RTE processing environment. FSIS recommends
maintaining the temperature below 50 °F in packaging areas for products that are to be refrigerated or frozen.
Because a moist environment is conducive to the growth of Lm, cooling units, air handling equipment, standing or dripping
water, and condensation all contribute to a very hospitable environment for the bacteria. If you stop the cause of standing
or dripping water, clean cooling units and air handling equipment at specific frequencies, and keep track of dates cleaned and
cleaning due dates, these preventive steps can make a difference in stopping the spread of Lm.
During repairs, production of RTE products should be stopped. All equipment and processing areas should be
cleaned and sanitized once operations resume after repairs are completed. Additionally, equipment and processing areas
should be tested for Lm or Listeria species before resuming RTE production.
It isn't just leaky roofs and broken air-conditioning units that need prompt attention. Rusty, pitted,
or peeling tools and equipment parts should be promptly replaced with new, smooth-surfaced ones.
Irregular surfaces can be difficult to clean and make for perfect hiding spots, or harborage sites, for Lm. Tools used
for RTE equipment should be cleaned and sanitized before each use. Equipment maintenance records and a monitoring program are
important so that damaged equipment can be repaired or replaced as soon as the need is identified.
Rats, mice, and insects are sources of Listeria and other microbial contamination. Effective rodent
and insect control programs play a critical role in preventing Lm from entering your plant and from
spreading throughout your facility, including into RTE processing areas.
Sanitizers are only effective if mixed as described in the manufacturer's instructions. Procedures should be in
place to ensure that sanitizer concentrations used on equipment, footbaths, and other food and non-food
contact surfaces are adequately maintained. Records should be kept to verify that the correct procedures were followed.
It's also important that employees understand that Lm can form biofilms if residual food is left on the equipment. Food contact
surfaces should be thoroughly cleaned and then sanitized so that biofilms are not given the chance to develop. Sanitizers should also
be rotated to ensure Lm does not develop resistance to particular sanitizers in use at the establishment.
Listeria Testing Program
To ensure that testing is as comprehensive as possible, maintain a record of all food contact surfaces (as required in
9 CFR 430) and environmental surfaces in the processing area to be tested. Ensuring that all of the identified surfaces are
actively sampled and have an equal opportunity of being selected for sampling will help make the results more meaningful.
Include the supporting documentation of the testing frequency in your Lm sanitation program, as well as supporting
documentation to support which alternative you are using in your HACCP, SSOP, or other prerequisite program, to support your claim
that Lm is not a hazard reasonably likely to occur in your product. Additionally, a key point to remember is that an
Lm testing program is a verification of the effectiveness of your food safety program to control this pathogen, not a
substitution for carrying out an effective control program.
By enacting a concerted approach with all 10 of these proactive measures, you can contribute immensely toward
the effort in preventing foodborne illness from Lm. FSIS' Small Plant Help Desk also has numerous resources to help
you prevent Lm contamination in your plant. Call (877) 374-7435 or send your inquiry to
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Generic Food Defense Plan Now Offered in Four Other Languages
By Jane Johnson
In its continuing effort to reach as many small and very small plant owners/operators as possible, FSIS' Office
of Outreach, Employee Education, and Training is pleased to announce that the generic food defense plan,
Food Defense Plan: Security Measures for Food Defense, has been translated into Spanish, Korean, Vietnamese, and
traditional Mandarin Chinese.
FSIS believes that it's essential for slaughter and processing plants under the Agency's jurisdiction to have
a functional food defense plan in place to increase the preparedness and ability of small plant owners and operators
to respond during an emergency. A functional food defense plan may reduce the risk of unsafe product and economic
loss, reduce theft, reduce the need for additional regulation on food defense, and reduce company liability.
The Food Defense Plan: Security Measures for Food Defense is a valuable tool for you because it's simple, easy
to understand, and can be modified to address the specific operation's needs better. The foreign language versions
are posted alongside the English language version on FSIS' Web site at
If you, or someone you know, need copies of this generic food defense plan and other food defense resources,
call the Small Plant Help Desk at (877) 374-7435. You can also send your request to InfoSource@fsis.usda.gov.
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Food Safety Resources
By Sally Fernandez
As you know, FSIS has regular podcasts on issues affecting small and very small plants. There's
a wide variety of topics these podcasts cover including labeling, risk assessment, and humane
For your convenience, FSIS' Office of Outreach, Employee Education, and Training has compiled all 70
podcasts from 2009 on one DVD. It's easy to order a free copy. Just fill out the order form from the Food Safety
Resources brochure you received in the mail and fax it to (202) 690-6524. To order a copy, go to
or call the Small Plant Help Desk at (877) 374-7435. You also can view the podcasts online at
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Commonly Asked Questions & Answers
Q. If a federally inspected establishment conducts custom exempt slaughter and
processing operations on the official premises, is it required to implement its SSOPs on the days that it conducts only custom
A. Yes. The regulations require that any time custom operations are conducted
in an official establishment, all of the provisions of 9 CFR Part 416 (sanitation) must apply to those operations
[9 CFR 303.1(a)(2) (i)]. Establishments operating under custom exemption also are required to document the
implementation and monitoring of the SSOPs and any corrective actions required [9 CFR 416.16(a)]. These records must be maintained
and be available to FSIS [9 CFR 416.16(c)].
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Small Plant NEWS
Editor: Keith Payne
Production: Joan Lindenberger, Sally Fernandez
Design: Gordon Wilson
Contact: Small Plant News, USDA/FSIS, Aerospace Building,
3rd Floor-Room 405, 14th and Independence Ave., SW, Washington,